准东探区侏罗系齐古组与头屯河组的划分

Dividing Qigu Formation and Toutunhe Formation of Jurassic in East Junggar Area

近年来的钻探表明,准噶尔盆地东部探区侏罗系石树沟群具有广阔的勘探前景,但是目前该套地层的层序划分存在很多问题,表现在南北露头剖面划分标准不统一,南部井下与地面露头划分原则和依据不一致,北部地区井下未进行层组划分。分析了本地区的构造演化、古环境、古气候的变化,确立了以岩石的颜色和沉积旋回作为石树沟群细分为齐古组与头屯河组的主要依据,并以此标准统一了准东探区井下及地面露头齐古组与头屯河组的划分问题,废除了将凝灰岩划分齐古组与头屯河组的划分标准。

The exploration practice in recent years shows that a broad prospect appears for exploration of Shishugou group of Jurassic in eastern Junggar basin. But now something is in question about its sequence classification. The dividing criterion of south-north outcrop sections are not the same; the southern wells differ from outcrop in dividing criterion, whereas the northern wells have not been divided in terms of available sequences. This paper analyzes the evolution of structure, paleo-environment and paleo-climate in this area, takes the rock color and sedimentary cycle as the primary bases for dividing Shishugou group into Qigu formation and Toutunhe formation, and thus solves the dividing problems between wells and outcrops in Qigu and Toutunhe formations in east Junggar basin. it is suggested that the previous criterion that uses tuff to divide these two formations should be repealed.